Leveling the back of a magazine follower is a standard part of the sporterizing process.
The rear of a magazine follower on a Mauser is designed for military use and milled at a 90-degree angle. This prevents the bolt from closing once the magazine is empty. We will need to alter the follower so the rear angle is about 45 degrees, like this commercial one.
To begin the process, clamp the follower in a padded vise and mark a guideline about half an inch back. Start grinding the follower down using a coarse file to the marked line.
Once you've reached the mark, switch to a smooth file, followed by abrasive paper, until you get a smooth finish.
It may be the easiest job when sporterizing a military Mauser action.
-- Larry Potterfield